404 on .well-known/acme-challenge/

Server
9

I definitely think /etc/nginx/sites-available/rails is the correct file after looking it over.

upstream app_server {
    server unix:/var/run/unicorn.sock fail_timeout=0;
}

server {
    listen   80;
    root /home/rails/rails_project/public;
    server_name _;
    index index.htm index.html;

    location / {
            try_files $uri/index.html $uri.html $uri @app;
    }

    location ~* ^.+\.(jpg|jpeg|gif|png|ico|zip|tgz|gz|rar|bz2|doc|xls|exe|pdf|ppt|txt|tar|mid|midi|wav|bmp|rtf|mp3|flv|mpeg|avi)$ {
                    try_files $uri @app;
            }

     location @app {
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $http_host;
            proxy_redirect off;
            proxy_pass http://app_server;
    }

    location ~ /.well-known {
            allow all;
    }

    location ~ /\.well-known/acme-challenge {
	root /usr/share/nginx/html;
    }
}